Air dispersion models and accounting for multiple vessels

Must air dispersion models that are used to analyze worst-case release scenarios under 40 CFR §68.25 be able to account for multiple vessels and how those vessels could impact one another in the event of an accidental release?

No. Models used for worst-case release scenario analysis do not need to consider compounding effects of accidental releases from multiple vessels because the worst-case release is based on a single vessel or process line failure that will result in the greatest distance to an endpoint (40 CFR §68.3).